HasOwnProperty check causes reactivity issues

[Tofandel]

Here is a demo

https://play.vuejs.org/#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

The issue is because of the hasOwnProperty check coming from the global Object prototype and not the Proxy one, the path which doesn't yet exist is never actually called on the proxy, which means vue has no way to track it

Replacing with !current.hasOwnProperty(pathPart) fixes the reactivity issue without introducing the vulnerability this code fixes

Thought?